Various methods exist for production of electronic grade silicon and its precursors. These methods include processes for the purification of silane before its reaction (e.g. thermal decomposition) to electronic grade silicon. For examples, see Walker et al., (U.S. Pat. No. 4,537,759), incorporated in its entirety herein, and the references therein.
Particular examples of contaminants of concern are ethylene and ethylsilane, which can be produced in the reactions to form silane. Distillation can be used to remove ethylsilane, leaving ethylene as a contaminant in the relatively purified silane composition. However, distillation of ethylene from silane can be difficult due in part to the compounds' close molecular weights and boiling points.
An alternative to distillation of ethylene from silane can be the use of molecular sieves. Although such sieves can be used effectively to separate ethylene from silane, such molecular sieve purification process itself can result in the production of ethylsilane and attending recontamination of silane with ethylsilane. There remains a need for further improvements in the separation of ethylene and silane with molecular sieves without an attending production of ethylsilane.